1. Technical Field
The present invention relates to a method for surface modification of non-dispersible metal nanoparticles and the metal nanoparticles for inkjet printing thus modified, in particular, to a method for surface modification of non-dispersible metal nanoparticles being used for paste to provide dispersity by chemical modification of the surface and metal nanoparticles thus modified, in which the surface modified metal nanoparticles are suitable for inkjet printing.
2. Description of the Related Art
As applications of nanoparticles are realized, a lot of effort of making and modifying a nano-structure in various ways is dramatically increased. Because of their superior catalytic property, nanoparticles, the major field of nano science, have gone deep into the study. Recently there have been many attempts to apply them to printed electronics. The reason why such nanoparticles are used in printed electronics is to further reduce the width of wirings used in electronic goods. In case of plating or coating existing bulk metal particles with paste method, it is hard to form a fine wiring. Therefore, metal nanoparticles with conductivity have been used for implement of ultra fine wirings.
There are broadly nanoparticles for paste and inkjet printing, based on applicative aspects. The biggest difference between nanoparticles for paste and those for inkjet printing is whether a capping molecule exists. Nanoparticles for paste is used for screen printing. Because the solvent of paste has a high viscosity and a dispersing agent is added additionally easily, there is no need for capping molecules. On the other hand, it is required to add a capping molecule to nanoparticles for inkjet printing to provide dispersion stability because when an additional dispersing agent is added in nanoparticles, it affects surface tension and viscosity of nanoparticles, which have a bad influence upon the ejection stability and decrease the conductivity when they have further applied to a conductive wiring.
Therefore, even though existing nanoparticles for paste are able for low-price mass production with the plasma method, there are problems with its applications for inkjet printing.